Experimental Boat Testing Tank Facility, Steyne Wood Battery

Experimental Boat Testing Tank Facility, Steyne Wood Battery

This is an experimental tank for testing model boats, housed within a purpose-built structure designed in 1910 by the engineering firm L G Mouchel for Sir John I Thornycroft.

The building is constructed of ferro-concrete, built using the Mouchel-Hennebique system. The experimental tank and its walls are of shuttered concrete. The flat roofs above the subsidiary areas on the north and south ends are constructed of breeze blocks covered with asphalt. The pitched roof above the experimental tank is supported by steel trusses and is part-glazed, part tile-clad.

The facility occupies a rectangular, two-storey building oriented roughly north-south. The experimental tank is housed centrally beneath a pitched roof. Two-storey flat-roofed sections flank the tank at either end of the building. Access to the upper floors is via external concrete stairs against the north elevation, which return onto an elevated walkway along the eastern side of the building. This walkway enters the building through a first-floor doorway at the south-east corner. Internally, the central tank is flanked by first-floor rooms to its south and north. Above the south end of the tank is a cantilevered gallery, and extending along the western side of the building is a cantilevered walkway. Both are accessed by steps to the south-west.

The exterior expresses the tank's location through its form: a pitched top-lit roof identifies the central tank area. This section is delineated by flues projecting above the eaves line and is flanked by two-storey flat-roofed sections. Bay divisions are marked by projecting concrete piers. The west elevation features concrete buttresses to support the weight of the tank internally and is blind in the central tank area. The east elevation's upper floor has ten multi-paned, timber-framed cross-casements with both side and top-hung lights. A concrete walkway with metal railings runs along the length of the building at this level, positioned between the floors. Below the walkway and between the projecting concrete piers are six angled glazed panels, which have the appearance of cold-frames and are understood to have been installed by Blanche Thornycroft as part of her interest in hydroponics (with water warmed by a boiler to the east of the building within the battery). The flat-roofed end sections are lit by windows of the same form as those on the east elevation. The south elevation comprises three bays, with a central four-panelled door providing ground-floor access, flanked by two three-light windows and a single central window above. The north elevation is largely blind except for a six-panelled door to the north-west (positioned off-centre because of the external stairs to the north-east) and a matching first-floor central window.

The tank, built along the north-south axis, measures 67 feet 6 inches long, 30 feet wide and 13 feet 9 inches deep. It was filled with fresh water pumped from a nearby well. The internal walls gently curve towards the base. Shallow extensions of the tank project to the south and north for the insertion and removal of models under test. This central zone is well-lit by the roof supported on steel trusses. The walkway along the western side of the tank overlooks it, as does the cantilevered gallery above the south end, both fitted with steel safety railings. Exposed pipes run along the west wall.

The subsidiary spaces at the north and south ends of the tank are separated from the tank by concrete columns and have lower ceiling heights due to their flat roofs. Each has a rectangular opening in its floor leading to the room beneath. On the ground floor, the room to the north contains a circular well (marked as 'pit' on the design drawings) measuring 20 feet deep and 3 feet wide, with a wall-mounted ladder and steel safety railings. A similar well is marked on the original plans for the south end of the building. Exposed pipework and a ceiling-mounted winch are also present.